Process for the preparation of methyl butenoate and its derivatives

ABSTRACT

PROCESS FOR THE PREPARATION OF METHYL 3,4-HYDROCARBYL3-BUTENOATES BY REACTION OF AN ALYLHALIDE   RR&#39;&#39;C=CR&#34;-CH2X   WHEREIN R, R&#39;&#39; AND R&#34; REPRESENT HYDROGEN OR A HYDROCARBYL HAVING FROM 1 TO 10 CARBON ATOMS AND X IS A HALIDE SELECTED FROM C1, BR, I, WITH CARBO MONOXIDE AND METHANOL. ONE OPERATES IN A METHANOL SOLUTION IN THE PRESENCE OF NCKEL-CARBONYL AND THIOUREA, AT ATMOSPHERIC PRESSURE, AT A TEMPERATURE BETWEEN 15* AND 35* C., MAINTAINING A PH RANGIN FROM 5.5 TO 9, AND PREFERABLY FROM 7.5 TO 8.

United States Patent O1 ABSTRACT OF THEDISCLOSURE Process for the preparation of methyl 3,4-hydroca'rbyl- 3-butenoates by reaction of an allyl halide wherein R, R and R" represent hydrogen or a hydrocarbyl having from 1 to 10 carbon atoms andX is a halide selected from Cl, Br, I, with carbon monoxide and methanol. One operates in :11 methanol solutioniin the presence of nickel-carbonyl and thiourea, 'atfatmospheric pressure, at a temperature between 15 and 35 C., maintaining a pH ranging from 5.5 to 9, and preferably from 7.5 to 8.

The present invention concerns a process for the preparation of butenoate and of its substitution derivatives in the allyl chain. More particularly, the process of this invention relates to the production of methyl 3-butenoate and its substitution derivatives in the allyl chain, by reacting an allyl halide with carbon monoxide and methanol in the presence of a catalyst.

The reaction scheme for obtaining methyl 3-butenoate, also called methyl vinylacetate, is:

wherein X stands for Cl, Br and I.

The methyl 3,4-hydrocarbyl-3-butenoates may be obtained analogously when in place of allyl halide the corresponding hydrocarbyl-propenylrhalides are used, according to the reaction scheme:

wherein R, R' and R" represent respectively hydrogen or a hydrocarbyl (alkyl, cycloalkylyaryl, arylalkyl). having from 1 to 10 carbon atoms and" X represents a'ha'logen selected from Cl, Br and I.

It is already known to prepare the'methyl 3-butenoate and its substitution derivatives in the-allyl chain, by using a catalytic system made of a Fe-Mn alloy in powder, nickel chloride and thiourea. This catalytic system is'capable to catalyze the introduction of the C0 intothe allyl halide molecule under rather simple working conditions and with good yields in butenoic ester. Neutralizers were used such as MgO or CaCO in order to eliminate the acidity, which is released during the reaction.-- a I have now found, and this forms the object of this invention, that it is possible to obtain methyl -3-butenoate and its derivatives of substitution in the allyl chain, by working in the presence of nickel-carbonyland thiourea in methanol "solution." Th6 'catalytivsystem usedirrthe Patented Apr. 25, 1972 process according to this invention is" formed in situ start ing from nickel carbonyl, thiourea and allyl halide in methanol. i i l My process offers particular advantages over the known methods. j p

Firstis the possibility of operating in a homogeneous phase. Second is the possibility of obtaining superior yields in butenoic esterysuch yields may attain up to 89%. Third is that the quantity of thiourea and nickel used is greatly reduced and that the nickel can easily be recovered atthe end of the reaction.

According to a preferred but not exclusive form of embodiment, the process according to this invention is carried out at a pH comprised between 5.5 and 9, but preferably between 7 .Sand 8. This pH is maintained constant-byneutralizing the acidity with an alkali soluble in methanol, such as for instance ammonia, sodium hydroxide or potassium hydroxide. The pH range within which one operates has an influence on the yield in butenoate with respect to the converted allyl halide, but even moreon the conversion of the allyl halide, and consequently on the catalytic efficiency of the process and on the reaction time.

The reaction is carried out in a CO atmosphere at atmospheric pressure, at. a temperature comprised between 15 and 35 C. Reaction times of from 5 to 8 hours are quite sufiicient.

For each mole of allyl halide at least 5 moles of methanol and from 0.01 to 0.1 mole of nickel-carbonyl are used; the thiourea, with respect to the nickel, is used in molar. ratios of from 0.5 :1 to 5:1, but generally of 2:1. Furthermore, .for a better working of the reaction, though not essential,*it is convenient to feed the nickel-carbonyl and the thiourea in small quantities during the course of the reaction;

At the end of the reaction, the components are distilled, after water has been added to them, in order to avoid'the precipitation of the inorganic halide (NH Cl, NaCl, KCl) during the distillation. The excess methanol and unreac'ted allyl halide may be recycled.

The recovery of the nickel salts may be carried out on the residue. This recovery is facilitated by the absence of other metal salts.

The methyl S-butenoate, and the obtained homologs represent raw materials of considerable applicative interest. Theyactually find a very convenient application in the preparation of reactive plasticizers for vinyl resins. Furthermore, said products may be easily isomerized to methyl 2-butenoates (methyl crotonate) or to its homologs which may be used as monomers for resins or as solvents.

By saponifying the methyl butenoate one obtains crotonic acid ..For this purpose, one operates by treating the methyl. butenoate with a small excess on the stoichioinetricof NaOH at 20-30% at a temperature of from to 90 C., for 13 hours. After acidification and extraction .with chloroform, one obtains a raw product constituting96% 'crotonicacid. By crystallization from heptane at 0C., one obtains pure crotonic acid. By. treating the methyl butenoate with an equal volume of sodium hydroxide at 2% in methanol, at room temperature, methyl crotonate is obtained. An appreciable amount (about 30%) of methyl 3-methoxy-butyrate is concomitantly formed, however, by addition of methanol to the double bond.

Methyl crotonate may also be obtained by stirring together, at 100 C., the methyl butenoate with Amberlite resin IR-45 (anionic resin of British Drug House). With 10% by weight of resin on the ester, after 3 hours one gets an isomerization of 55%. Upon continuation of the treatment, one gets a fast drop of the isomerization rate. In fact, one attains 70% only after 10 hours. At much lower temperatures the isomerization rate is considerably lower;

attains thus, a 50 C., with a 30% by weight of resin, one 47% of isomerization only after-8 hours.

The crotonic acid finds use as a comonomer of viny acetate in the field of adhesives, of textile and paper auxiliaries, of water-paints'and in the preparation of polyester photographic films. The 4,6-dinitro-2,l-methylheptyl-phenyl crotonate, under the name of Karathane, is used as weed killer. Other esters of similar structure display a pesticidal and fungicidal activity. As n-butyl ester,-it is a raw material for plasticizers. The .crotonicacid isalso used in the preparation of cellulose esters (cellulose acetocrotonates) for the production of films or binders for the paint and varnish industry. i

The following examples are given to better illustrate but not limit this invention. I 1 EXAMPLE 1 The equipment consists of a S-necked 5 liter flask, provided with a thermometer, a mechanical stirrer, dropping funnels for the feeding of the reactants, a glass electrode and a calomel reference electrode for measuring the pH, and connecting pipe with a CO tank. The calomel electrode is in contact with the solution through aglasstube fu of :1 KCl saturated solution. This tube; at the end dipped in the reaction mixture, is closed by a porous pop. celain bottom plate. I Q

Into .the flask, after washing with CO, were introduced dried under vacuum, weighed 'very viscous brown-liquid. 7

1.4 g. and appeared as a The water, already extracted with CHCl was acidified and extracted with ether."There were present 0.18 g. of vinylacetic acid.

the whole 7.2 g. ofnickel-carbonyl, 7.3 g. of thinurea'arid 119.59g. of allyl-chloride had been used (cohversion: 97.2%; recovered: 3.48 g.). i Y

There wereobtained: 1,5-hexadiene: 1.36 g. equal to 2.18% on the converted C H Cl; methyl butenoate plus methyl crotonate: 139.7 g.=89.4%

on the converted-C H5Cl; v

" allyl vinylacetatez' 0.46 g.-=0.42% oh -the converted C H Cl. H V y W EXAMPLE 2 Into a'' 100" cc. flask providedwitha water' cooler, a

dropping funnel and a magnetic stirrer, were introduced s'sjc. Thereaf er; there were added 20, cc. of H20 in 750 cc. of CH OH, 125 g. of allyl-chloride at 98.5.%, 4g.

of thiour'ea and 5.28 g. of Ni(CO) This mixture was stirred maintaining the temperature at between 22 and 23 C. The solution turned into an intense red shade, while a development of CO (about one liter) was observed during the first 5 minutes, after which set in the absorpj 7 tion of the gas. The pH value was maintainedat 7.58 by a dropwise addition of methanol saturated with NI-I at After minutes from the start of the absorption of the gas, 0.3 g. of thiourea were dipped in 4 cc. of CH OH, an'd every 30 minutes, up to 4 hours and 30mihutes, then, at 5 hours and 15 minutes from the start another addition was made, and at 6 hours 15 minutes fromgthe start' still another addition was made. After 7 hours, when. theabsorption of gas attainsthe valuejof 30 liters and is-practieally stopped, the ammonium chloridewas 1} thereupon filtered off and the reaction mixture was subjected to fractional distillation after 400 cc. of H 0 had been added. The following fractions wereobtained:

fraction up to 64 C. (31:3 g.), besides methanol,

tains: 1,5-hexadiene (1.3' g. allyl-chloride( 3.2 g. isoallyl-chloride (1 g.); fraction between 64 and 65 C. (1028 g.) besides meth anol, contains: 1,5-hexadiene (0.06 g.), allyl-chloride (0.28 g.), methyl butenoate (22.8 g.); fraction 65-85" C. (34 g.), contains methanol and methyl butenoate (21g); 1 I y fraction 84-87 C. (azeotrope with water) g.ltheio rgani c phase weighs 92.6 g. and contains. methyl butenoate orderto dissolve the precipitated salt, and by cooling the mixture with water or ice, this was acidified with H 80 at 10% up ma pH 4. With further water the possible precipitate of Na SO was then dissolved and it was continuously extracted with CHCI for} hours.

The CHCl was then distilled at a reduced pressure and the raw substance was dissolved in 40 cc. of boil-" ing heptane. By cooling down to 0 0., there was obtained the crystallization of the crotonic acid which, filtered and dried-under'vacuum, weighed'13;4' g.jand had "a melting point of 71:C. -(yield of 71.2% on the starting VA). (VA is vinylacetate.) In the heptane solution were found by gas-chromatography, 0.12 g. of crotomate; by successive esterification of the acids present with 'diazomethane', by: gas-chromatography, were found 0.7 g. of vinylacetic acid (equal to 3.7% of the starting VA and 4.7- of crotonic'acid (equal to 24.8% of the starting VA). The residual solution may be recycled to crystallize further raw substance.

- EXAMPLE '3 U11 the" same equiipment as that described in Example 1, and following the same procedures and using the same quantities of reactants, other tests were carried'out at different pH, values. The results are recorded on the following table; A I

v TABLE Range of pH values 5. 5-6 645. 5 6. 5-7 7-7. 5 7.5-8

Conversion percent of the a 5 48 76 92. 3 92. 1 27. 2 Percent on the CsHsCl eonvetted lnto: p

1,5-hexadlene 8. 1 3. 55 2. 58 2. 45 2. 18 Methyl butenoate plus methyl erotonate. 75. 5 86 5 B8. 9 S9. 3 Allyl vinylthioacetate 0. 4. 0. 83 1. 41 v 0. 43 H 0. 42 U'ndi'stilled residue i'n g 0. 9 2. 6 l" 1. '4 Molar ration q a.

,VA zN 24. 5 30.. 2 31. 2 33. 2 VAzTU.-. 10.8 10.3 13.8

-91.4 g.), methyl crotonate (0.9 g.) and methanol The undistilled residue together with the water, which remains in the flask after the azeotropic'distillationimas extracted with CHCI and chlorotormic [so tion (was in turn extracted with NaHCO In the alkalinesqlution,

which had been acidified and extracted withf'e'the'r, no i viuylacetic acid was present. The chloroformic extract,

wherein R,"R' and R" represent hydrogen or a hydrocarbyl having from 1 to 10 carbon atoms, by reaction of an allyl halide RR'C=OR"CH X wherein R, R and R" have the above-indicated meaning and X is a halide selected from Cl, Br and I, with carbon monoxide and methanol, wherein one operates in a methanol solution in the presence of nickel-carbonyl and thiourea, at atmospheric pressure, at a temperature between 15 and 35 C., and a pH range maintained from 5.5 to 9.

2. The process of claim 1, wherein the pH is from 7.5 to 8.

3. The process according to claim 1, wherein the pH is kept constant by neutralizing the acidity with an alkali, soluble in methanol, selected from ammonia, sodium hydrate and potassium hydroxide.

4. The process according to claim 1, wherein from 0.01 mole to 0.1 mole of nickel-carbonyl are used per References Cited FOREIGN PATENTS 9/1962 France 260-486 10/1965 Japan 260-48S 0 JAMES A. PA'IT-EN, Primary Examiner P. I. KILLOS, Assistant Examiner US. Cl. X.R.

260410.9 R, 468 CB, 469, 481 R, 680 R 

